Big thanks to New Paralyzer for the help with this.
When you make it to the Dam, Nina will give you an objective to acquire a Cavity Magnetron.
1: Leave her office, walk all the way to the right and enter the elevator.
2: In the staff room, head back to the oven and interact with it to get the Cavity Magnetron.
3: Leave via the window again. Once outside, select it from your inventory, and use it with the glowing water beneath you.
Your achievement should now unlock.